Also, if I wanted to tell that in the same sentence:
Konnichi wa, watashi wa Ruji desu, watashi wa Portugal kimashita.
What can I replace the underlined expression for, in case I don't want to repeat myself?

Also, if I wanted to tell that in the same sentence:Konnichi wa, watashi wa Ruji desu, watashi wa Portugal kimashita.What can I replace the underlined expression for, in case I don't want to repeat myself?

You leave it out (which you can do even if you leave it as two sentences), and in compound sentences like that, the desu becomes de.